Excel - STDEV (1st, 2nd, 3rd) and excluding datapoints

Asked By To on 08-Jun-08 09:37 PM

Excel 2003 SP3
3000+/- data points in a row-by-row listing (A2 through A3001)
STDEV provides the 1st standard deviation.
1) Unless I'm missing something, how do I do 2nd and 3rd standard deviation
calculations?
2) Some of my data is 'fringe' data. That is, by eyeballing the data I'm
seeing some data that doesn't easily 'fit'.
a) Can I eliminate the 'fringe' data somehow via a formula?
b) Can I analyze ONLY the 'fringe' data?
c) How do I quantify the 'fringe' data for exclusion or inclusion?
3) Some insight into 2nd/3rd standard deviations would be appreciated
relative to Excel 2003.
TIA!

joeu2004 replied on 11-Jun-08 06:26 AM

It is called a column.
2*STDEV(...) and 3*STDEV(...).
Elimination of "fringe" data is a debatable issue. Avoid doing it
unless and until you know more about statistics.
(You could google for the term "outliers". But again, it is a
debatable issue, especially for you.)